1. Field of the Invention
The present invention relates to an electrical connector for receiving a printed circuit board, and more particularly to an electrical connector having a latching device for releasably securing the printed circuit board.
2. The Prior Art
In order to facilitate insertion of a daughter board into a slot of a connector, front portions of terminals within the slot are specially designed such that the daughter board encounters zero force during insertion. In general, the front portions of the terminals are cantilevered and can be biased. Conductors of the daughter board are electrically and mechanically connected with the terminals after the daughter board is inserted and rotated to engage with the connector. Not only can the daughter board be easily inserted, but the height of the daughter board and connector will also be reduced. However, during rotation, the front portions of the terminals are pushed away from their original positions and the resulting biasing force tends to push the daughter board away therefrom. Thus, the daughter board must be locked with respect to the connector to prevent disengagement between the conductors and the front portions of the terminals.
Latching mechanisms have been developed to retain daughter boards in place in a connector housing. Such latching mechanisms are typically either directly formed in the structure of the connector housing at opposite ends thereof, or they may be separately formed and inserted into the connector housing. Latches integrally formed with the housing do not provide an adequate retention force. Latches formed from a metal strip provide an excellent retention force but manufacturing costs are increased. U.S. Pat. Nos. 4,986,765, 5,514,002, and 5,632,640 disclose pertinent designs.
Hybrid latches, made from both plastic and metal material, are introduced to address the above mentioned drawbacks. Taiwan Patent Nos. 81102107, 81400686, 84100813 and U.S. Pat. Nos. 4,986,765, 5,004,429, 5,145,396, 5,514,002, 5,632,640 disclose connectors having hybrid latches. An integrally formed plastic portion is used to retain a clipping portion of the daughter board and a metal portion is used to release the daughter board from the plastic portion. The metal portion is separated from the housing. However, even though such latches provide improved resilience and strength, the plastic portion tends to break when an excess force is exerted thereon.
In order to prevent the plastic portion from breaking, the housing is provided with a stopper to limit movement of the plastic portion. This inevitably increases the length of the connector and hinders the compactness thereof. In addition, plastic stoppers are not durable thereby hindering resilience of the plastic portion. Furthermore, in locking or releasing the daughter board, the hybrid latches are pushed away from their original positions. The plastic portion often breaks during this stage because a junction between the plastic portion and the housing experiences a concentration of stress. The junction is a curved plane without any reinforced member mounted thereon.
Hence, an improved electrical connector is needed to overcome the disadvantages of the prior art.